Large field of view metrology: detecting critical edge placement error signatures not seen with small field of view in an HVM environment

Abstract

For advanced nodes, a robust metrology is required to estimate EPE and its contributors. Especially when moving to late process development steps (Ramp-Up and High Volume Manufacturing (HVM)) where inter and intra wafer variations are small but crucial. In this study, we used 8um by 8um SEM images to assess the benefit of large Field-of-View (LFOV) metrology. The result proves the capability of LFOV metrology in capturing not only intra-wafer EPE behavior and its sensitivity to minor variations but also the minor wafer-to-wafer (W2W) variations which is not possible using a small FOV (SFOV) metrology (0.5um by 0.5um) due to larger noise level.